1. Field of Invention
The present invention relates to broadband and spectrally-tuned circularly-polarizing reflective microflakes made from non-absorptive film material such as cholesteric liquid crystal (CLC) film material, and more particularly to a method of making super-white, mirror-like and additive-primary colored inks, paints and crayons embodying the same, for employment in additive-primary type coloring systems requiring radiation absorbing substrates.
2. Brief Description of Prior Art
In U.S. Pat. No. 5,364,557, Applicant has taught how to make CLC pigments for use in various applications. The advantage of using such CLC pigments is that color characteristics can be imparted to images painted and printed therewith by virtue of the reflection polarizing properties of CLC materials. In color printing, and in the fine arts, CLC color inks are known to possess much higher color saturation and brightness than conventional pigment and dyed based inks. This is in contrast with conventional pigments made from inorganic dyes where the color characteristics thereof are imparted to images painted and printed therewith by virtue of the absorption properties of such materials. A direct consequence of the absorption properties of prior art pigments based on inorganic dyes is that they are characterized by low reflection characteristics over their respective spectral bands. This makes the colors less bright than would otherwise be desired in many applications where a premium is provided for highly reflective paints, surface coatings, and the like, e.g. in the automotive industries, in particular.
However, CLC-based pigments based on the teachings of Applicant""s U.S. Pat. No. 5,364,557 are not without shortcomings and drawbacks.
For example, Applicants have discovered that the reflection characteristics of prior art CLC-based microflakes differ on different sides of every CLC microflake. Consequently, as it is impossible to control microflake surface arrangement during application, the color purity and brightness characteristics of color coatings formed by prior art CLC microflakes are generally non-uniform and inadequate for commercial utility.
Moreover, when painting or printing on radiation absorptive surfaces (e.g. black paper) using CLC-based coloring media having xe2x80x9cadditivexe2x80x9d primary color characteristics (e.g red, green and blue), there arises a great need for a CLC-based coloring media having xe2x80x9cwhitexe2x80x9d color characteristics in order to render color images with a full range of color shades and intensities, naturally required by human artistic expression. However, the only way in which to obtain the xe2x80x9cperfect whitexe2x80x9d color characteristics using CLC-based coloring media having red, green and blue color characteristics, is to additively mix together CLC-based coloring media having xe2x80x9cidealxe2x80x9d (i.e. spectrally pure) red, green and blue color characteristics, which have very narrow spectral reflection characteristics as shown in FIGS. 1A1, 1A2, and 1A3. FIG. 1B shows the spectral reflection characteristics produced when CLC-based coloring media having xe2x80x9cidealxe2x80x9d red, green and blue color characteristics are additively mixed together to produce xe2x80x9cimperfect whitexe2x80x9d color characteristics.
In practice, however, CLC-based coloring having xe2x80x9cactualxe2x80x9d red, green and blue color characteristics have relatively wide spectral reflection characteristics, as graphically illustrated in FIGS. 1C1, 1C2 and 1C3. Consequently, when xe2x80x9cactualxe2x80x9d CLC-based coloring media having red, green and blue color characteristics are added together, it is not possible to produce the xe2x80x9cperfect whitexe2x80x9d color characteristics, but only xe2x80x9cimperfect whitexe2x80x9d color characteristics having spectral reflection characteristics as graphically illustrated in FIG. 1D. As a result, when painting or printing with CLC-based coloring media having xe2x80x9cactualxe2x80x9d red, green and blue color characteristics, the color shade and balance of color images produce thereby invariably fall far short of the sought after ideal color characteristics made available using other coloring mediums.
Consequently, when using the prior art CLC-based coloring media taught in U.S. Pat. No. 5,364,557, it has been impossible to produce color images capturing the colorful aspects of nature in a faithful manner, nor produce color images having color tones and shades demanded by even those endowed with low levels of artistic expression.
Thus there is a great need in the art for a system and method of forming highly-reflective full-color images using coloring media that avoids the shortcomings and drawbacks of prior art printing and painting systems and methodologies.
Accordingly, it is a primary object of the present invention to provide reflective microflakes for use in xe2x80x9csuper-whitexe2x80x9d and xe2x80x9cadditive-primaryxe2x80x9d coloring media (e.g. colored inks, paints, and crayons) while avoiding the shortcomings and drawbacks of prior art printing and painting systems and methodologies.
Another object is to provide such reflective microflakes made from circularly polarizing reflective material having improved spectral and band-pass position characteristics for imparting improved color characteristics.
Another object of the present invention is to provide such microflakes with a laminated construction, wherein each surface thereof exhibits symmetrical broadband reflection characteristics over particular regions of the visible band of the electromagnetic spectrum, in order to provide improved light reflectively and brightness when used in the manufacture of colored inks, paints and/or crayons of the present invention.
Another object of the present invention to provide such microflakes made from microscopic size fragments of thin CLC film material in which the axis of helical pitch of CLC molecules extends along the thickness dimension of the CLC microflake (i.e. transverse to the surface thereof), and in which the pitch of the helices of the CLC molecules varies in a non-linear (e.g. exponential) manner along the thickness dimension of each CLC microflake.
Another object of the present invention is to provide such CLC microflakes with a laminated construction, wherein each surface thereof normal to the helical axis exhibits symmetrical broadband reflection characteristics over the visible band of the electromagnetic spectrum, in order to provide improved light reflectively and brightness when used in the manufacture of super-white polarizing inks, paints and/or crayons of the present invention.
Another object of the present invention is to provide CLC microflakes which have reflection characteristics over the visible band of the electromagnetic spectrum which provide improved light reflectively and brightness when used in the manufacture of super-white polarizing inks and/or paints of the present invention.
Another object is to provide CLC microflakes made from both left-handed and right-handed circularly polarizing material having circularly-polarizing reflection characteristics over the entire visible band of the electromagnetic spectrum, for improved color characteristics.
Another object is to provide a method of fabricating CLC microflakes from circularly polarizing material having extremely broadband spectral reflection and transmission characteristics, low optical loss properties, high polarizing efficiency and low manufacturing cost.
Another object is to provide a method of fabricating circularly polarizing reflective microflakes having broadband spectral characteristics, low optical loss properties, high polarizing efficiency, simplified fabrication, and low manufacturing cost.
Another object of the present invention is to provide a novel method of fabricating broadband CLC-based pigments by producing CLC polymer films having liquid crystal molecules arranged along helical axes normal to the surface of the film, and then fragmenting the CLC film into flat flakes or platelets of microscopic size and thereafter mixing them in a suitable carrier medium for application onto the surface of particular radiation absorbing substrate.
Another object is to provide a method of fabricating CLC-based microflakes using a mixture of polymerizable CLC, liquid crystal material and a photoinitiator, wherein during polymerization of the polymerizable CLC, the segregation rate of the liquid crystal material is constrained to be greater than the polymerization rate of the polymerizable CLC being polymerized.
Another object is to provide a method of fabricating broadband CLC microflakes, in a way which does not employ ultraviolet dye during the manufacture thereof.
Another object is to provide a method of fabricating broadband circularly polarizing reflective microflakes, wherein the polymerizable CLC being polymerized is exposed to a non-linear (e.g. exponential) intensity gradient of actinic (e.g. UV) radiation by virtue of light loss within the polymerizable CLC medium, thereby causing a non-linear variation in pitch of helices of the CLC molecules therein.
Another object is to provide a method of fabricating super broadband circularly polarizing reflective microflakes using commercially available constituent cholesteric liquid crystal polymers and liquid crystal material.
Another object of the present invention is to provide super-white CLC-based colorants comprising broadband circularly polarizing reflective microflakes which have helical axes normal to the surfaces thereof and different thickness which, when suspended in an optically transparent carrier medium and applied to a substrate, produce a coating which reflects broadband circularly polarized light falling incident thereon in a non-specular manner to produce a super-white color appearance in the eyes of onlooking observers akin to conventional Magnesium Oxide based paints and inks.
Another object of the present invention is to provide mirror-like CLC-based colorants comprising broadband circularly polarizing reflective microflakes which have helical axes normal to the surfaces thereof and different thickness which, when suspended in an optically transparent carrier medium and applied to a substrate, produce a coating which reflects broadband circularly polarized light falling incident thereon in a specular manner to produce a mirror-like color appearance in the eyes of onlooking observers akin to conventional plate-mirror surfaces.
Another object of the present invention is to provide a novel set of CLC-based paints and/or inks for forming on radiation absorbing substrates, images created from a palette of colors comprising super-white and the additive primary colors (i.e. pure red, pure green, and pure blue).
Another object of the present invention is to provide a novel coloring system comprising a set of CLC-based inks and paints that can be applied to radiation absorbing substrates at room temperature allowing artists, painters and the like to form images having super-white color characteristics similar to conventional Magnesium Oxide based inks and paints, and which after drying at room temperature, retain their remarkable color characteristics.
Another object of the present invention is to provide super-white ink and paint, in which the pigment is realized by broadband circularly-polarizing reflective microflakes made from CLC film material.
Another object of the present invention is to provide a novel method for making super-white CLC-based inks and paints containing double-layer CLC microflakes having highly symmetrical broadband reflection characteristics that enable reflection of 100% of ambient light in a non-specular manner to produce super-white color characteristics when viewed under prespecified lighting conditions.
Another object is to provide a method of fabricating CLC-based microflakes from broadband free-standing circularly polarizing reflective CLC film.
Another object of the present invention is to provide a novel method of making super-white CLC inks and paints that can be applied at room temperature and without the need for alignment or measures in order to impart non-specular reflecting properties thereto.
Another object of the present invention is to use such a novel coloring system in order to produce 3-D stereo images (prints, paints and plots).
Another object of the present invention is to provide super-white CLC pens, pencils, and crayons for painting and printing applications.
Another object of the present invention is to provide apparatus for generating a three-dimensional image including two unmultiplexed images in stereoscopic relationship with each other, wherein one of the images is produced using CLC ink (or paint) of the present invention that is reflects left-handed circularly polarized broadband light, while the other image is produced using CLC ink (or paint) of the present invention that is reflects right-handed circularly polarized broadband light.
Another object of the present invention is to provide a novel method and system for 3-D stereo printing, painting and plotting using the CLC-based inks and paints of the present invention to produce brighter and higher quality images than achievable using prior art materials and methods.
Another object of the present invention is to provide 3-D images that are produced by conventional printing and plotting means in conjunction with left hand and right hand polarizing CLC inks, paints or other transfer media.
An even further object of the present invention is to provide CLC-based toner material for use in conventional xerographic printers and copiers.
Another object of the present invention is to provide various types of CLC-based toner material for the xerographic printing of single-color monocular images, full-color monocular images, single-color stereoscopic images, and full-color monocular images.
Yet another object of the present invention is to provide a system and method producing secured documents by printing information contained therein with invisible polarization-selective inks or toner.
Another object of the present invention is to provide such a system and method of producing secured documents, in which the invisible polarization-selective inks or toner is made from CLC-based microflakes.
These and other objects of the present invention will become apparent hereinafter and in the claims to Invention.